Why is the changes of the content of register related to cash access?

Question:

Why should the program that changes the content of register (CCR1, CCR2) related to cash access the cache effective area after reading the content of the register related to cash?

Answer:

It will take some time from the time the instruction which CPU updates the register related to cash such as CCR1 and CCR2 is executed to the time the value of these registers is actually updated.

Such a limitation is applied because there is a possibility of doing operation different from the users' intentions when the cache-enabled area is accessed before the update of the register related to cash is completed.